tumors, the most common malignancy in men 15-35 years of age (1); however, primary mediastinal seminoma is rare among extragonadal germ cell tumors (2).
□
CASE REPORT
□
Mediastinal Seminoma with an Elevated Level of Serum Angiotensin-converting Enzyme Hiroshi Ishii 1, Fumiyasu Igata 1, Kazuki Nabeshima 2, Hisako Kushima 3 and Kentaro Watanabe 1
Abstract A 22-year-old man was admitted following the detection of right hilar enlargement during a medical checkup. The patient’s serum angiotensin-converting enzyme (ACE) level was abnormally high, and a needle aspiration biopsy showed non-caseating epithelioid cell granulomas. Surgical resection was performed, and the resected specimens showed irregularly shaped seminoma nests with intervening stroma consisting of epithelioid cell granulomas. Furthermore, immunohistochemistry demonstrated ACE expression in the epithelioid cells and some tumor cells. The patient’s serum ACE level declined after the surgery and subsequent systemic chemotherapy, indicating the presence of tumor-induced sarcoid-like reactions rather than the coexistence of seminoma and sarcoidosis. Key words: angiotensin-converting enzyme, mediastinal tumor, sarcoidosis, sarcoid-like reaction, seminoma (Intern Med 54: 1909-1912, 2015) (DOI: 10.2169/internalmedicine.54.3953)
Introduction
Case Report
Seminomas account for one-third of testicular germ cell tumors, the most common malignancy in men 15-35 years of age (1); however, primary mediastinal seminoma is rare among extragonadal germ cell tumors (2). Sarcoidosis is a granulomatous disease of unknown etiology characterized by the presence of non-caseating epithelioid cell granulomas, most often located in the lungs or hilar and/or mediastinal lymph nodes, although any organ can be affected. While the detection of an elevated serum angiotensin-converting enzyme (ACE) level may be helpful in the diagnosis of sarcoidosis, the gold-standard is the presence of epithelioid cell granulomas in involved organs. In addition, although there have been several reported cases of testicular seminoma occurring concomitantly with a suspected diagnosis of sarcoidosis, it is unclear whether the granulomas indicate the presence of sarcoidosis or rather reflect sarcoid-like reactions against tumor antigens (3). We herein describe a rare case of primary mediastinal seminoma with an elevated serum level of ACE.
A 22-year-old Japanese non-smoking man without any respiratory symptoms was admitted after right hilar enlargement was detected during a medical checkup (Fig. 1A). The patient had undergone resection of a retroperitoneal teratoma at 4 months of age and resection of a testicular venous aneurysm at 12 years of age and had been found to have mild mental retardation since 6-7 years of age. There were no abnormal findings on a physical examination, including a skin assessment, chest auscultation and SpO2 measurement. Chest computed tomography (CT) showed an anterior mediastinal mass (Fig. 1B) that was positive (maximum standardized uptake value: SUVmax =8.39) on positron emission tomography (PET) with fluorodeoxyglucose (Fig. 1C); however, no abnormal imaging findings were detected in the other organs. Meanwhile, the laboratory findings indicated a serum ACE level of 72.8 U/L (normal range: 8.3-21.4 U/L), a β subunit of human chorionic gonadotropin (β-HCG) level of 12 mIU/mL (normal range:
